胶北高级变质基底中高压基性麻粒岩的地球化学特征及其成因

胶北高级变质基底中高压基性麻粒岩主要由石榴基性麻粒岩、石榴紫苏麻粒岩和石榴斜长角闪岩所组成,并主要以不规则透镜体或变形岩墙的形式赋存于TTG质片麻岩或花岗质片麻岩之中。胶北高压基性麻粒岩在变质过程中,以大离子亲石元素(K、Na、Sr、Rb)为代表的活动元素发生了显著的改变;而高场强元素(Th、Nb、Zr、Ti)和稀土元素基本无变化,保持稳定。胶北高压基性麻粒岩属于拉斑玄武质岩石系列,其SiO2集中变化于44.04%～53.54%,Mg#值集中变化于35～60之间;稀土配分曲线不仅存在总量较低的平坦型(ΣREE=21.13×10-6～78.49×10-6,(La/Yb)CN=1.03～2.86),也有轻稀土相对富集且含量相对较高的右倾型(92.74×10-6～133.5×10-6,(La/Yb)CN=2.93～4.56),Eu异常不明显(Eu/Eu*=0.93～1.04)。高压基性麻粒岩Cr、Ni含量变化较大,但与MgO含量具有很好的相关性。与显生宙岛弧拉斑玄武岩一样,胶北高压基性麻粒岩几乎所有样品皆具有Nb、Zr、Ti负异常,且εNd(t)为正值(+2.70～+4.77)。综合分析认为,胶北高压基性麻粒岩具有岛弧拉斑玄武质岩石的地球化学特征,其原岩可能为弧后扩张背景下侵入的辉长岩或辉绿岩,以及相应喷出的基性火山岩。     

北秦岭丹凤地区早古生代花岗岩的Pb、Sr、Nd同位素地球化学特征

通过对北秦岭丹凤地区早古生代花岗岩的Ph、Sr、Nd同位素地球化学特征的系统研究,结合元素地球化学特征,证明早古生代具成分极性的枣园、黄柏岔、石门花岗岩是由于秦岭群斜长角闪岩和黑云斜长片麻岩部分熔融,近俯冲带以熔体与熔体的混合、远离俯冲带是前者产生的熔体与后者熔融后的残留相以不同比例混合形成的。     

北秦岭丹凤地区早古生代花岗岩的Pb、Sr、Nd同位素地球化学特征

通过对北秦岭丹凤地区早古生代花岗岩的Ｐｈ、Ｓｒ、Ｎｄ同位素地球化学特征的系统研究，结合元素地球化学特征，证明早古生代具成分极性的枣园、黄柏岔、石门花岗岩是由于秦岭群斜长角闪岩和黑云斜长片麻岩部分熔融，近俯冲带以熔体与熔体的混合、远离俯冲带是前者产生的熔体与后者熔融后的残留相以不同比例混合形成的。     

胶北地块变质基底超镁铁岩的矿物岩石地球化学特征

胶北地块变质基底的蛇纹岩、蛇纹岩化尖晶石方辉橄榄岩、尖晶石橄榄斜方辉石岩、角闪石岩自形成以后,经历了早期的高角闪岩相和晚期绿片岩相的变质作用,因而记录了三个阶段的矿物组合:早期的Opx1+Ol1+Spl1;中期的Opx2+Ol2+Spl2+Amp2和晚期的Amp3+Srp3+Mag3+Cal组合。超镁铁岩中普遍存在的角闪石,具有粒状变晶结构特征,形成于角闪岩相和绿片岩相的变质作用过程。蛇纹石没有受到应力作用的迹象,显示其形成于晚期非挤压环境的交代变质作用过程。尖晶石橄榄岩中斜方辉石的矿物化学以及尖晶石橄榄岩的高Mg O含量都表现出克拉通橄榄岩的性质。角闪石岩的稀土元素配分图解的(La/Sm)N的比值1.11~1.41,(La/Yb)N的比值0.91~1.61,超镁铁岩多元素图解显示无高场强元素异常,都表明胶北地块变质基底的超镁铁岩形成的构造背景或是裂谷环境。尖晶石矿物的Mg#0.72~0.79、Cr#0.06~0.12表明交代变质成因。方辉橄榄岩橄榄石的Fo值88.42~90.50、超镁铁质岩石全岩主元素的分散性、较大的∑REE含量变化以及Si/Al-(Mg+Fe)/Al和Mg/Ti-Fe/Ti主元素的比值图解所表现出的超镁铁岩与角闪石岩具有成因联系等,都表明胶北变质基底的超镁铁岩可能是具有堆晶成因的一套幔源岩浆系列。高MgO含量(16%~42%)表现出前寒武纪变质基底的橄榄岩地幔性质;高水含量反映出漫长地质历史时期变质作用过程。     

中国西北地区早古生代柴达木北缘超高压变质带的大陆俯冲：证据来自此带中发现柯石英

作者使用激光拉曼微光谱在柴达木北缘超高压变质带与一大型榴辉岩体有关的泥质片麻岩的锆石单矿物中发现柯石英。柯石英呈包体产出。此外,还发现一些石墨包体。这发现表明曾发生原地超高压变质作用。地体很可能是在低于金刚石稳定区压力条件下结晶的。     

大别超高压变质过程中部分熔融作用的地球化学约束

报道了大别超高压变质带西部麻城四道河榴辉岩-围岩剖面系统的元素和同位素地球化学研究成果, 对超高压变质榴辉岩在俯冲和折返过程中的部分熔融作用进行了探讨. 研究表明, 榴辉岩原岩性质类似于N-MORB, 其长英质围岩可分为TTG片麻岩和含石榴石花岗岩; 两类长英质围岩Sm -Nd同位素特征与其寄主的榴辉岩相似; REE特征、w (Nb)/w (Ta) 比值、Nd同位素组成及锆石U -Pb定年等地球化学证据支持了TTG片麻岩为大别地区陆壳俯冲过程中发生部分熔融作用而形成, 其与超高压榴辉岩的关系属特殊的异地关系; 含榴花岗岩为超高压榴辉岩折返过程中的部分熔融作用形成, 但因其形成环境为石榴石稳定场的深度, 故含榴花岗岩与超高压榴辉岩被视为近似原地的构造关系.      

内蒙古中部构造混杂带晚古生代-早中生代变质基性岩的地球化学特征及其大地构造意义

内蒙古中部构造混杂带中的变质基性岩可分为南、北两带:南带位于乌兰沟-图林凯地区,被划分至温都尔庙群下部的桑达来因组,主要为一套变质玄武岩和辉长岩、辉绿岩,局部含有超基性岩和碳酸岩透镜体,其中变质基性火山岩以绿片岩相变质为主,局部保留枕状构造或发育蓝片岩,已有的锆石U-Pb年代学数据表明南带变质基性火山岩形成于晚古生代到早中生代;北带位于芒和特-二道井-红格尔一线,主要呈岩块状保存在由绢云绿泥石英片岩、硅质岩、含铁石英岩和少量的大理岩组成的基质中,岩石类型包括蓝片岩、冻蓝闪石片岩、阳起片岩、绿帘角闪片岩等。地球化学研究显示南、北两带的变质基性岩相对低Al(Al2O3=10.66%~14.97%)、低Ti(TiO2=1.27%~1.96%)、高Na(Na2O=1.02%~4.20%)、贫K(K2O=0.02%~0.71%),具有拉斑玄武岩到碱性玄武岩系列的过渡特征,高的Na2O/K2O比值(6.89~454)暗示这些基性岩在变质作用前发生了细碧角斑岩化。不活动元素Zr与其他高场强元素(HSFE;Th、Nb、Hf、Ti)和稀土元素(REE)显示良好的线性关系,表明在变质过程中,高场强元素和稀土元素基本保持稳定,可以反映原岩的性质。根据稀土、微量元素配分型式和相关比值可以将内蒙中部构造混杂带中的变质基性岩分为两类:一类稀土含量相对较低(∑REE=46.00×10-6~78.08×10-6)、轻重稀土分异不明显((La/Yb)N=0.50~1.04),无明显Eu负异常,Hf/Ta=6.82~15.18,具有正常的大洋中脊玄武岩(NMORB)特征;另一类稀土含量相对较高(∑REE=58.66×10-6~151.3×10-6)、轻重稀土分异明显((La/Yb)N=2.28~4.68),无明显Eu负异常,Hf/Ta=2.06~4.70,与富集型洋中脊玄武岩(E-MORB)相似。部分变质基性岩样品轻微富集大离子亲石元素Rb和Ba,可能暗示原岩在就位过程中遭受了微弱的陆壳混染。以上地球化学特征表明这些变质基性岩的原岩可能形成于一个扩张规模有限的陆内洋盆环境。已有的古生物地理学研究表明古亚洲洋闭合后,到晚古生代早期,内蒙古中部地区成为佳-蒙地块的一部分。石炭纪期间整个内蒙古中部发育稳定的浅海相沉积,局部为造山后隆起环境,发育加里东I型花岗岩和花岗闪长岩。从晚石炭世-早二叠世起,内蒙中部开始处于伸展环境:二连浩特到东乌珠穆沁旗一带发育大量的碱性岩;华北克拉通北缘发育很多高钾钙碱性-碱性的花岗岩;内蒙中部地区广泛发育二叠纪大石寨组双峰式火山岩。到中二叠世开始裂解形成若干近东西向分布的海盆,发育哲斯组、林西组浅海相、泻湖相沉积。持续的伸展形成了有限洋盆,发育以温都尔庙群为代表的含铁硅质岩以及晚古生代-早中生代基性岩。由于早中三叠世华北板块与扬子板块全面碰撞和陆内造山过程的影响,有限洋盆最终在早中生代之后发生被动闭合,形成南、北构造混杂带,并导致该基性岩乃至整个内蒙中部的晚古生代沉积发生广泛绿片岩相变质作用,而局部蓝片岩的形成可能与有限洋盆的俯冲作用有关。     

塔里木地区早古生代海平面波动特征:来自地球化学及岩溶的证据

下古生界是塔里木盆地内最有潜力找到大油气田的层位。通过盆地内48口钻至下古生界钻井的沉积层序与沉积相分析、9800km地震剖面的地震相分析、大量Sr、C同位素及微量元素分析,并结合相关资料,开展了寒武纪—奥陶纪的以世或期为单位的岩相古地理研究,定性探讨海平面变迁。在此基础上,运用沉积地球化学定量探讨海平面的波动。分析表明,早古生代塔里木地区经历了两次大规模的海侵与海退过程,寒武纪和奥陶纪各经历了一次。每个海侵与海退过程内各包含了两个较高频的海平面升降旋回,即早寒武世早期海侵—早寒武世中期至中寒武世晚期海退、中寒武世末期海侵—晚寒武世晚期海退、早奥陶世早期至中奥陶世中期海侵—中奥陶世晚期海退、晚奥陶世早期海侵—晚奥陶世中至晚期海退。在上述2次大规模的海侵与海退以及4个较高频的海平面升降旋回中,两次大的海侵分别发育于早寒武世早期以及晚奥陶世早中期,三次较大的海退出现于中寒武世晚期、晚寒武世末期、晚奥陶世早期。岩溶在地层格架中的发育支持了上述结论。     

北阿尔金地区早古生代洋壳俯冲时限:来自斜长花岗岩和花岗闪长岩的证据

蛇绿岩在不同演化阶段自身形成的花岗质岩石和侵入到蛇绿岩中的花岗质岩石对于蛇绿岩的精确定年具有重要意义,是揭示洋壳俯冲时限的有力证据。对北阿尔金红柳沟—拉配泉蛇绿岩中斜长花岗岩和花岗闪长岩的锆石U-Pb及Lu-Hf同位素分析表明,红柳沟斜长花岗岩和花岗闪长岩的锆石LA-ICP-MS U-Pb定年结果分别为(501±3)Ma和(496±2)Ma,表明北阿尔金洋的俯冲时限可能开始于中寒武世或更早。斜长花岗岩和花岗闪长岩的锆石εHf(t)值均为正值,结果分别为1.6~5.6和3.3~6.9,反映其源区均为亏损型地幔。全岩地球化学分析结果表明,斜长花岗岩具有高Si O2、高Sr、低Y和相应的高Sr/Y等类似于埃达克质岩石的特征,可能来自热的洋壳俯冲到石榴角闪岩相条件下变基性岩发生小比例部分熔融形成,且其形成深度应该在40~50 km;花岗闪长岩属于高钾钙碱性系列岩石,可能代表了岛弧环境下下地壳基性岩石部分熔融的产物。年代学分析表明,北阿尔金洋可能存在南北双向俯冲,并且北阿尔金洋向北俯冲可能略早于向南俯冲。北阿尔金和北祁连的俯冲时限对比研究表明,北阿尔金早古生代缝合带是北祁连早古生代缝合带的西延部分。     

北秦岭弧后盆地俯冲消减与陆壳物质再循环——桃园岩体和黄岗杂岩体的地球化学证据

对桐柏北部加里东期桃园岩体和黄岗杂岩体的地球化学研究表明, 桃园岩体形成于与洋壳消减作用有关的弧后盆地环境, 与二郎坪基性火山岩具有相同的岩浆来源.黄岗杂岩岩浆中含有一定比例的陆壳物质, 该物质来自俯冲板片上陆壳沉积物的再循环, 与二郎坪弧后盆地向北的俯冲消减有密切联系.      

Quartz and feldspar zoning in the eastern Erzgebirge volcano-plutonic complex (Germany, Czech Republic): evidence of multiple magma mixing

Zoned quartz and feldspar phenocrysts of the Upper Carboniferous eastern Erzgebirge volcano-plutonic complex were studied by cathodoluminescence and minor and trace element profiling. The results verify the suitability of quartz and feldspar phenocrysts as recorders of differentiation trends, magma mixing and recharge events, and suggest that much heterogeneity in plutonic systems may be overlooked on a whole-rock scale. Multiple resorption surfaces and zones, element concentration steps in zoned quartz (Ti) and feldspar phenocrysts (anorthite content, Ba, Sr), and plagioclase-mantled K-feldspars etc. indicate mixing of silicic magma with a more mafic magma for several magmatic phases of the eastern Erzgebirge volcano-plutonic complex. Generally, feldspar appears to be sensitive to the physicochemical changes of the melt, whereas quartz phenocrysts are more stable and can survive a longer period of evolution and final effusion of silicic magmas. The regional distribution of mixing-compatible textures suggests that magma mingling and mixing was a major process in the evolution of these late-Variscan granites and associated volcanic rocks.

Quartz phenocrysts from 14 magmatic phases of the eastern Erzgebirge volcano-plutonic complex provide information on the relative timing of different mixing processes, storage and recharge, allowing a model for the distribution of magma reservoirs in space and time. At least two levels of magma storage are envisioned: deep reservoirs between 24 and 17 km (the crystallisation level of quartz phenocrysts) and subvolcanic reservoirs between 13 and 6 km. Deflation of the shallow reservoirs during the extrusion of the Teplice rhyolites triggered the formation of the Altenberg-Teplice caldera above the eastern Erzgebirge volcano-plutonic complex. The deep magma reservoir of the Teplice rhyolite also has a genetic relationship to the younger mineralised A-type granites, as indicated by quartz phenocryst populations. The pre-caldera biotite granites and the rhyodacitic Schönfeld volcanic rocks represent temporally and spatially separate magma sources. However, the deep magma reservoir of both is assumed to have been at a depth of 24–17 km. The drastic chemical contrast between the pre-caldera Schönfeld (Westfalian B–C) and the syn-caldera Teplice (Westfalian C–D) volcanic rocks is related to the change from late-orogenic geotectonic environment to post-orogenic faulting, and is considered an important chronostratigraphic marker.     

樊家川油田储层渗流单元分析及其剩余油分布

樊家川油田已进入开发后期,为了精确预测层内剩余油潜力,解剖更小级别的储层非均质单元分布,在储层沉积微相研究的基础上,应用储层FZI值进行单一河流沉积单元的渗流单元划分,并讨论了成因砂体与渗流单元的关系以及渗流单元中剩余油分布规律,从而提高了剩余油预测的精度。     

Timing of the progress granite,Larsemann hills: Additional evidence for early Palaeozoic orogenesis within the east Antarctic Shield and implications for Gondwana assembly

The Progress Granite is one of numerous S‐type granitoid plutons exposed in the Larsemann Hills region, southwest Prydz Bay, east Antarctica. The granite was emplaced into a migmatitised pelitic to felsic paragneiss sequence during a regional high‐grade transpressional event (D₂) that pre‐dates high‐grade extension (D₃). SHRIMP (II) U‐Pb dating for two occurrences of the Progress Granite from D₂ and D₃ structural domains gives ²⁰⁶Pb/²³⁸U ages of 516.2 ± 6.8 Ma and 514.3 ± 6.7 Ma, respectively. These ages are interpreted as crystallisation ages for the Progress Granite and confirm Early Palaeozoic orogenesis in the Larsemann Hills region. This orogen appears to have evolved during continental convergence and is probably responsible for widespread radiogenic isotopic resetting and the near‐complete exhumation of the adjacent northern Prince Charles Mountains which evolved during a ca 1000 Ma event. The identification of a major Early Palaeozoic orogen in Prydz Bay allows tentative correlation of other domains of Early Palaeozoic tectonism both within the east Antarctic Shield and other, once contiguous, Gondwana fragments and illustrates the potential complexity inherent within intercratonic mobile belts. One such possibility, tentatively offered here, suggests a continuous belt of Early Palaeozoic tectonism from Prydz Bay eastward to the West Denman Glacier region and into the Leeuwin complex of Western Australia.     

元素地球化学特征在识别碳酸盐岩层序界面中的应用——以冀北坳陷中元古界高于庄组为例

元素是组成岩石矿物的基本单元,它们对环境的变化极为敏感。地层中元素的分配及比值变化、组合都在一定程度上纪录着古沉积环境的演化历程,这些对恢复古沉积环境,研究海相碳酸盐古盐度、海平面相对变化具有重要的指示意义。利用元素地球化学特征对冀北坳陷中元古界高于庄组层序地层单元进行研究,发现在古气候的影响下,古盐度、相对海平面变化与碳酸盐中的元素含量及有关元素比值呈现明显的旋回变化特征。其中Sr/Ba比值法与硼法判别精度相对较高,可以作为识别和划分碳酸盐岩层序界面的有效标志。     

The Early Palaeozoic Break-up of Northern Gondwana: Sedimentology, Physical Volcanology and Geochemistry of a Submarine Volcanic Complex in the Bavarian Facies Association, Saxothuringian Basin, Germany

Ordovician volcano-sedimentary successions of the Bavarian facies association in the Saxothuringian basin record the continental rift phase of the separation of the Saxothuringian Terrane from Gondwana. An 80 m succession from the Vogtendorf beds and Randschiefer Series (Arenig-Middle Ordovician), exposed along the northern margin of the Münchberg Gneiss Massif in northeast Bavaria, were subjected to a study of their sedimentology, physical volcanology and geochemistry. The Randschiefer series previously has been interpreted as lavas, tuffs, sandstones and turbidites, but the studied Ordovician units include four main lithological associations: mature sandstones and slates, pillowed alkali-basalts and derivative mass flow deposits, trachyandesitic lavas and submarine pyroclastic flow deposits interbedded with turbidites. Eight lithofacies have been distinguished based on relict sedimentary structures and textures, which indicate deposition on a continental shelf below wave base. The explosive phase that generated the pyroclastic succession was associated with the intrusion of dykes and sills, and was succeeded by the eruption of pillowed basalts. Debris flow deposits overlie the basalts. Ordovician volcanism in this region, therefore, alternated between effusive and explosive phases of submarine intermediate to mafic volcanism.

Based on geochemical data, the volcanic and pyroclastic rocks are classified as basalts and trachyandesites. According to their geochemical characteristics, especially to their variable concentrations of incompatible elements such as the High Field Strength Elements (HFSE), they can be divided into three groups. Group I, which is formed by massive lavas at the base of the succession, has extraordinarily high contents of HFSE. The magmas of this group were probably derived from a mantle source in the garnet stability field by low (ca. 1%) degrees of partial melting and subsequent fractionation. Group II, which comprises the pillow lavas at the top of the sequence, displays moderate enrichment of HFSE. This can be explained by a slightly higher degree of melting (ca. 1.6%) for the primary magma. Group I and II melts fractionated from their parental magmas in different magma chambers. The eruption centres of Groups I and II, therefore, cannot be the same, and the volcanic rocks must have originated from different vents. The sills and pyroclastic flow deposits of Group III stem at least partly from the same source as Group I. Rocks of Group I most likely mixed together with Group II components during the formation of the Group III flows, which became hybridised during eruption, transportation and emplacement.

The sedimentological and geochemical data best support a rift as the tectonic setting of this volcanism, analogous to modern continental rift zones. Hence, the rift-associated volcanic activity preserved in the Vogtendorf beds and Randschiefer Series represents an early Ordovician stage of rift volcanism when the separation of the Saxothuringian Terrane from Gondwana had just commenced.     

Microstructural timing of the Rosebery massive sulphides, Tasmania: evidence for a metamorphic origin through mobilization of disseminated base metals

Microstructural timing relationships indicate that the Rosebery massive sulphide ore, western Tasmania, Australia, formed by metasomatic replacement of 'sericite' schist during a Devonian deformation event (D3). This interpretation is contrary to earlier volcanogenic-based interpretations, but accords with the discordant position and inferred structurally controlled emplacement of the orebody. The main timing criteria are: overprinting of S3 by the late ore minerals, replacement textures in undeformed mineral parageneses, and a D3 structural control from the microscopic to the macroscopic scales. The consistent observation of these criteria in the orebody and the complete lack of pre-D3 ore argue against in situ dissolution of a primary orebody and local redeposition of sulphides by replacement.
D3 deformation at Rosebery is inferred to have been characterized by heterogeneous cleavage-parallel extension, which resulted in localized microfracturing and selective replacement of zones of maximum strain rate. Continuous shifts in the strain-rate distribution pattern during progressive mineralization led to the compositional ore banding.
Published Pb-isotope data point towards a Cambrian source rock for the orebody. This suggests a metamorphogenic origin by regional-scale dissolution of dispersed volcanogenic metals, focused solution transfer and concentrated redeposition in a structural trap.     

The effect of heterogeneous stress and strain on metamorphic fluid flow,Mary Kathleen,Australia, and a model for large-scale fluid circulation *

In the Proterozoic Mary Kathleen Fold Belt, northern Australia, infiltration of large volumes of externally derived fluid occurred synchronously with regional amphibolite-facies metamorphism and deformation. This paper develops a model of structurally controlled fluid migration by comparing the distribution of fossil fluid pathways with the inferred stress and strain patterns during the deformation. Intense fluid flow was localized within strong, relatively brittle meta-intrusive bodies, and in discrete, veined, brecciated and altered zones around their margins. In metasediments folded in a ductile manner outside these areas, fluid infiltration was negligible. The direct correlation between structural styles and the magnitude of veining and metasomatism suggests control of permeability enhancement, and hence fluid flow, by deformation. Finite difference modelling of a strong body in a weaker matrix has been used to evaluate the variation of stresses during the deformation, from which it is clear that stress and strain heterogeneities have systematically influenced the development and maintenance of metamorphic fluid pathways. Particular regions in which mean stress may be significantly lower than the average lithostatic pressures include the ‘strain shadow’zones adjacent to the strong bodies, other dilatant zones around the bodies, and the bodies themselves. This geometry is favourable not only for localized brittle deformation under amphilobite facies conditions, but also for focused fluid flow in the low mean stress regions, as evidenced by the abundance of veins. Fluid access through these metamorphic aquifers occurred during tensile failure episodes, with particularly large dilations and decimetre-scale veining in areas of strain incompatibility. It appears likely that fluid circulated many times through the Fold Belt, with flow concentrated in the metamorphic aquifers. A model is developed that explains both the structurally focused fluid flow and the postulated multi-pass recirculation by dilatancy pumping, the ‘pump engines’comprising the low mean stress zones.     

滇西梁河—潞西地区新生代英安岩的源区及成因——来自地球化学的证据

报道了滇西梁河—潞西地区新生代英安岩的主量、微量、稀土元素和Nd同位素地球化学研究成果。英安岩富集轻稀土元素、大离子亲石元素(Rb、Th、U、K),相对亏损重稀土元素和Nb、Ta、Sr、P、Ti,具有Eu负异常和Pb正异常。火山岩的εNd(0)为-10.3~-8.72,Nd同位素模式年龄(tDM)为1.2~1.4Ga。这些地球化学特征表明,研究区英安岩源于区域基底岩系的部分熔融,并与该地区同期幔源玄武质岩浆发生了不同程度的混合。     

滇西梁河—潞西地区新生代英安岩的源区及成因——来自地球化学的证据

报道了滇西梁河—潞西地区新生代英安岩的主量、微量、稀土元素和Nd同位素地球化学研究成果。英安岩富集轻稀土元素、大离子亲石元素(Rb、Th、U、K),相对亏损重稀土元素和Nb、Ta、Sr、P、Ti,具有Eu负异常和Pb正异常。火山岩的εNd(0)为-10.3~-8.72,Nd同位素模式年龄(tDM)为1.2~1.4Ga。这些地球化学特征表明,研究区英安岩源于区域基底岩系的部分熔融,并与该地区同期幔源玄武质岩浆发生了不同程度的混合。     

华北克拉通北缘崇礼—赤城地区的红旗营子(岩)群:一套晚古生代的变质杂岩

分布在华北克拉通北缘中段崇礼—赤城地区的红旗营子(岩)群主要由变质表壳岩、晚古生代的闪长质—石英闪长质片麻岩和古元古代—新太古代的变质岩残片或残块组成。利用SHRIMP和LA-ICPMS法对红旗营子(岩)群变质表壳岩的锆石同位素年代学研究表明,变质表壳岩样品中除大量古元古代—新太古代的锆石年龄信息外,还有许多中元古代—晚古生代的锆石,且均有晚古生代甚至早中生代的多阶段变质作用的记录。这些证据表明红旗营子(岩)群并非早前寒武纪岩石建造,而是一套晚古生代的变质杂岩。红旗营子(岩)群周围侵入体的锆石U-Pb测年表明岩浆作用与变质作用具有较好的相关性,它们与中亚造山带多阶段的俯冲、碰撞造山和后造山伸展事件相关。由于红旗营子杂岩中含有晚古生代退变榴辉岩和变质方辉橄榄岩,这可能意味着华北克拉通北缘的冀北地块在晚古生代早期曾经从华北克拉通上裂开,在中亚造山带古亚洲洋板块俯冲作用的影响下又重新拼合,红旗营子杂岩代表华北克拉通北缘的冀北地块与华北克拉通在晚古生代重新拼合的俯冲碰撞拼贴带。